Capacitive touch button with guard

ABSTRACT

An apparatus, such as a set-top box, includes at least one capacitive touch button with a guard feature that provides, among other things, the ability to detect and reject false touches. According to an exemplary embodiment, the apparatus includes a first conductive element that is capacitively isolated from ground, and a second conductive element that is capacitively isolated from ground and located adjacent to the first conductive element. A first sensor is coupled to the first conductive element and measures a change in capacitance between the first conductive element and ground due to a change in physical environment. A second sensor is coupled to the second conductive element and measures a change in capacitance between the second conductive element and ground due to the change in physical environment. A controller is coupled to the first sensor and the second sensor and determines a difference between the measured changes in capacitance of the first sensor and the second sensor.

This application claims the benefit, under 35 U.S.C. §365 ofInternational Application PCT/US2012/037915, filed May 15, 2012, whichwas published in accordance with PCT Article 21(2) on Apr. 10, 2014 inEnglish.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure generally relates to user input mechanisms, andmore particularly, to any type of device, apparatus and/or system havingat least one capacitive touch button with a guard feature that provides,among other things, the ability to detect and reject false touches.

Background Information

This section is intended to introduce the reader to various aspects ofart, which may be related to the present embodiments that are describedbelow. This discussion is believed to be helpful in providing the readerwith background information to facilitate a better understanding of thevarious aspects of the present disclosure. Accordingly, it should beunderstood that these statements are to be read in this light.

Home and mobile user devices often include one more buttons as part of auser interface. These interfaces may often rely on using one or morecapacitive touch type buttons in place of more conventional tactile orpositive pressure type buttons. With a capacitive touch button there maybe no mechanical feedback to indicate that a button press has occurred.This can result in user confusion and/or frustration. For example, withcertain conventional electronic devices (e.g., set-top boxes, etc.), itmay be relatively easy for a user to accidentally turn the device offwhile simply repositioning the device if, for instance, the user putshis or her palm over a capacitive power button of the device. Oneapproach for attempting to reject false positives is to simply changethe sensitivity of a capacitive sensor associated with the capacitivetouch button. However, such an approach alone is deemed less thanoptimal.

Accordingly, there is a need in the art to address the foregoing issuesand thereby provide an improved design for a capacitive touch button.The present embodiments described herein address these and/or otherissues.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present disclosure, an apparatus isdisclosed. According to an exemplary embodiment, the apparatus includesa first conductive element that is capacitively isolated from ground,and a second conductive element that is capacitively isolated fromground and located adjacent to edges of the first conductive element. Afirst sensor is coupled to the first conductive element and measures achange in capacitance between the first conductive element and grounddue to a change in physical environment. A second sensor is coupled tothe second conductive element and measures a change in capacitancebetween the second conductive element and ground due to the change inphysical environment. A controller is coupled to the first sensor andthe second sensor and determines a difference between the measuredchanges in capacitance of the first sensor and the second sensor.

In accordance with another aspect of the present disclosure, a method isdisclosed. According to an exemplary embodiment, the method includesmeasuring a change in capacitance between a first conductive element andground due to a change in physical environment; measuring a change incapacitance between a second conductive element and ground due to thechange in physical environment, wherein the second conductive element islocated adjacent to substantially all surface edges of the firstconductive element; and determining a difference between the measuredchanges in capacitance.

The aforementioned summary of preferred and exemplary embodiments of thepresent disclosure is merely illustrative of the inventive conceptspresented herein, and is not intended to limit the scope of the presentdisclosure in any manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of thisdisclosure, and the manner of attaining them, will become more apparentand the disclosure will be better understood by reference to thefollowing description of embodiments of the disclosure taken inconjunction with the accompanying drawings, wherein:

FIG. 1 shows a general block diagram of a system according to anexemplary embodiment of the present disclosure;

FIG. 2 shows a more detailed block diagram of a receiving apparatusaccording to an exemplary embodiment of the present disclosure;

FIG. 3 shows a configuration including a capacitive touch button withguard according to an exemplary embodiment of the present disclosure;

FIG. 4 shows an exemplary sensor circuit according to an embodiment ofthe present disclosure;

FIG. 5 shows a capacitive sensor element arrangement according to anexemplary embodiment of the present disclosure;

FIG. 6 shows a capacitive sensor element arrangement according toanother exemplary embodiment of the present disclosure;

FIG. 7A and FIG. 7B show a view of a capacitive touch button with guardwith various user inputs according to an exemplary embodiment of thepresent disclosure; and

FIG. 8 shows a flow diagram according to an exemplary embodiment of thepresent disclosure.

The exemplifications set out herein illustrate preferred embodiments ofthe disclosure, and such exemplifications are not to be construed aslimiting the scope of the disclosure in any manner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It should be understood that the elements shown in the figures may beimplemented in various forms of hardware, software or combinationsthereof. Preferably, these elements are implemented in a combination ofhardware and software on one or more appropriately programmedgeneral-purpose devices, which may include a processor, memory andinput/output interfaces. Herein, the phrase “coupled” is defined to meandirectly connected to or indirectly connected with through one or moreintermediate components. Such intermediate components may include bothhardware and software based components.

The present description illustrates the principles of the presentdisclosure. It will thus be appreciated that those skilled in the artwill be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of thedisclosure and are included within its scope.

All examples and conditional language recited herein are intended foreducational purposes to aid the reader in understanding the principlesof the disclosure and the concepts contributed by the inventor tofurthering the art, and are to be construed as being without limitationto such specifically recited examples and conditions.

Moreover, all statements herein reciting principles, aspects, andembodiments of the disclosure, as well as specific examples thereof, areintended to encompass both structural and functional equivalentsthereof. Additionally, it is intended that such equivalents include bothcurrently known equivalents as well as equivalents developed in thefuture, i.e., any elements developed that perform the same function,regardless of structure.

Thus, for example, it will be appreciated by those skilled in the artthat the block diagrams presented herein represent conceptual views ofillustrative circuitry embodying the principles of the disclosure.Similarly, it will be appreciated that any flow charts, flow diagrams,state transition diagrams, pseudocode, and the like represent variousprocesses which may be substantially represented in computer readablemedia and so executed by a computer or processor, whether or not suchcomputer or processor is explicitly shown.

The functions of the various elements shown in the figures may beprovided through the use of dedicated hardware as well as hardwarecapable of executing software in association with appropriate software.When provided by a processor, the functions may be provided by a singlededicated processor, by a single shared processor, or by a plurality ofindividual processors, some of which may be shared. Moreover, explicituse of the term “processor” or “controller” should not be construed torefer exclusively to hardware capable of executing software, and mayimplicitly include, without limitation, digital signal processor (DSP)hardware, read only memory (ROM) for storing software, random accessmemory (RAM), and nonvolatile storage.

Other hardware, conventional and/or custom, may also be included.Similarly, any switches shown in the figures are conceptual only. Theirfunction may be carried out through the operation of program logic,through dedicated logic, through the interaction of program control anddedicated logic, or even manually, the particular technique beingselectable by the implementer as more specifically understood from thecontext.

In the claims hereof, any element expressed as a means for performing aspecified function is intended to encompass any way of performing thatfunction including, for example, a) a combination of circuit elementsthat performs that function or b) software in any form, including,therefore, firmware, microcode or the like, combined with appropriatecircuitry for executing that software to perform the function. Thedisclosure as defined by such claims resides in the fact that thefunctionalities provided by the various recited means are combined andbrought together in the manner which the claims call for. It is thusregarded that any means that can provide those functionalities areequivalent to those shown herein.

The present disclosure relates to an apparatus and method that controlsthe operation of a capacitor touch button or capacitive touch panel. Theapparatus and method address problems associated with unintentionaltouches to the button or touch panel by providing discrimination betweencontact, or touching, intended for a button and contact, or touching,that covers the button along with an area around the button. Althoughthe embodiments described below primarily focus on use in a set top boxreceiver device setting, aspects of the present disclosure may equallyapply to other consumer and commercial devices that utilize touchbuttons or touch panels including, but not limited to, computers,tablets, cellular phones, televisions, internet or product kiosks, andthe like.

Referring now to the drawings, and more particularly to FIG. 1, ageneral block diagram of a system 100 according to an exemplaryembodiment of the present disclosure is shown. As indicated in FIG. 1,exemplary system 100 comprises a signal source 10, a receiving apparatus20 and a display device 30. According to an exemplary embodiment, system100 may represent a digital satellite receiving system in which signalsource 10 is embodied as a satellite antenna and receiving apparatus 20is embodied as a digital set-top box, gateway and/or other device.However, this type of arrangement is exemplary only, and system 100 mayrepresent other types of systems, such as systems operative to receiveand process signals provided via cable, terrestrial, internet and/orother signal sources.

According to exemplary embodiments, receiving apparatus 20 is operativeto receive and process signals in analog and/or digital modulationformats provided via signal source 10, and provide output signalssuitable for display via display device 30. According to principles ofthe present disclosure, receiving apparatus 20 comprises a user inputportion 40 that utilizes capacitive touch sensor technology, andincludes at least one capacitive touch button with a guard feature. Aswill be described later herein, the aforementioned type of capacitivetouch button with guard feature advantageously provides, among otherthings, the ability to detect and reject false button touches.

Referring now to FIG. 2, a more detailed block diagram of a receivingapparatus 200 according to an exemplary embodiment of the presentdisclosure is shown. Receiving apparatus 200 of FIG. 2 may operate in amanner similar to receiving apparatus 20 described in FIG. 1 and may,for example, be included as part of a gateway device, modem, set-topbox, or other similar communications device. Receiving apparatus 200 mayalso be incorporated into other systems including an audio device or adisplay device. In either case, several components necessary forcomplete operation of the system are not shown in the interest ofconciseness, as they are well known to those skilled in the art.

In FIG. 2, content is received by receiving apparatus 200 via an inputsignal receiver 202. Input signal receiver 202 may be one of severalknown receiver circuits used for receiving, demodulating, and decodingsignals provided over one of the several possible networks includingover the air, cable, satellite, Ethernet, fiber and phone line networks.The desired input signal may be selected and retrieved by input signalreceiver 202 based on user input provided through a control interface(not shown) or a touch panel interface 222.

Touch panel interface 222 may include an interface for a touch screendevice. Touch panel interface 222 may also be adapted to interface to acellular phone, a tablet, a mouse, a high end remote or the like.According to exemplary embodiments, touch panel interface 222 may alsoemploy capacitive touch sensor technology, and include at least onecapacitive touch button with a guard feature, as referenced above inconjunction with FIG. 1, and further described below.

The decoded output signal of input signal receiver 202 is provided to aninput stream processor 204. Input stream processor 204 performs thefinal signal selection and processing, and includes separation of videocontent from audio content for the content stream. The audio content isprovided to an audio processor 206 for conversion from the receivedformat, such as compressed digital signal, to an analog waveform signal.The analog waveform signal is provided to an audio interface 208 andfurther to the display device or audio amplifier. Alternatively, audiointerface 208 may provide a digital signal to an audio output device ordisplay device using a High-Definition Multimedia Interface (HDMI) cableor alternate audio interface such as via a Sony/Philips DigitalInterconnect Format (SPDIF). Audio interface 208 may also includeamplifiers for driving one more sets of speakers. Audio processor 206also performs any necessary conversion for the storage of the audiosignals.

The video output signal from input stream processor 204 is provided to avideo processor 210. The video signal may be one of several formats.Video processor 210 provides, as necessary, a conversion of the videocontent, based on the input signal format. Video processor 210 alsoperforms any necessary conversion for the storage of the video signals.

A storage device 212 stores audio and video content received at theinput. Storage device 212 allows later retrieval and playback of thecontent under the control of a controller 214 and also based on commands(e.g., navigation instructions such as fast-forward (FF) and rewind(Rew)) received from a user interface 216 and/or touch panel interface222. Storage device 212 may be a hard disk drive, one or more largecapacity integrated electronic memories, such as static RAM (SRAM), ordynamic RAM (DRAM), or may be an interchangeable optical disk storagesystem such as a compact disk (CD) drive or digital video disk (DVD)drive.

The converted video signal provided from video processor 210, eitheroriginating from the input or from storage device 212, is provided todisplay interface 218 which further provides the display signal to adisplay device of the type described above. Display interface 218 may bean analog signal interface, such as red-green-blue (RGB), or may be adigital interface such as HDMI.

Controller 214 is interconnected via a bus to several of the componentsof receiving apparatus 200, including input stream processor 202, audioprocessor 206, video processor 210, storage device 212, and userinterface 216. Controller 214 manages the conversion process forconverting the input stream signal into a signal for storage on thestorage device or for display, and also manages the retrieval andplayback of stored content. Controller 214 also provides control outputsin response to user inputs via user interface 216 and touch panelinterface 222.

Controller 214 is further coupled to control memory 220 (e.g., volatileor nonvolatile memory, including RAM, SRAM, DRAM, ROM, programmable ROM(PROM), flash memory, electronically programmable ROM (EPROM),electronically erasable programmable ROM (EEPROM), etc.) for storinginformation and instruction code for controller 214. Control memory 220may store instructions for controller 214, and may also store a databaseof elements, such as text and/or graphic elements containing content.

User interface 216 ideally includes a front panel assembly containingone or more buttons. According to exemplary embodiments, at least one ofthese buttons employs capacitive touch sensor technology and is embodiedas a capacitive touch button with a guard feature, as referenced abovein conjunction with FIG. 1, and further described below.

Referring to FIG. 3, a configuration 300 including a capacitive touchbutton with guard according to an exemplary embodiment of the presentdisclosure is shown. Exemplary configuration 300 may be employed invarious different types of devices, apparatuses and/or systems, such asreceiving device 20 of FIG. 1 and/or receiving device 200 of FIG. 2. Asindicated in FIG. 3, exemplary configuration 300 comprises a firstconductive element 310, a second conductive element 320, a first sensor330, a second sensor 340, and a controller 350.

According to exemplary embodiments, first conductive element 310 iscapacitively isolated from ground and represents a main portion of acapacitive touch button, and second conductive element 320 iscapacitively isolated from ground and represents a guard portion of thecapacitive touch button. First and second conductive elements 310 and320 may be embodied, for example, as conductive pads. The capacitivetouch button may represent, for example, a main, or power, button of theapplicable apparatus, device and/or system.

Also according to exemplary embodiments, second conductive element 320is located adjacent to substantially all surface edges of firstconductive element 310. Furthermore, the second conductive element 320may be concentric with the first conductive element 310. A gap 315exists between first and second conductive elements 310 and 320. Suchgap 315 may be uniform along the respective surface edges of first andsecond conductive elements 310 and 320, or may vary as a matter ofdesign choice. The gap 315 may include only an air gap, or alternativelymay include another dielectric and nonconductive material. Additionally,a conductive ground surface (not shown) may be present either outsidethe conductive element 320 or, alternatively, below the first conductiveelement 310 and/or the second conductive element 320. The gap betweenthe conductive ground surface and the conductive elements 310 and 320may include an air gap or may include a dielectric material.

In the exemplary embodiment of FIG. 3, first conductive element 310 isshown as a circular element and second conductive element 320 extendscircumferentially around substantially all of first conductive element310 in a ring-like manner. The shape and size of second conductiveelement 320 (i.e., the guard portion) can be modified to allow fordifferent types of presses. For instance, a user interface directly infront of the user would work well poking directly at the center of thepad. A horizontal touch interface may allow the user to lay their fingermore horizontally. In this case, second conductive element 320 could becut away to prevent detecting it as a false press.

Accordingly, the configuration of FIG. 3 is exemplary only, and othertypes of complementary shapes may be used for first and secondconductive elements 310 and 320 to thereby form different types ofcomplementary configurations in which second conductive element 320 islocated adjacent to substantially all surface edges of first conductiveelement 310. As referred to herein, “substantially all” means two-thirdsor more.

According to another exemplary embodiment, second conductive element 320may be located adjacent to, and extend around, only half or more of thesurface edges of first conductive element 310. According to yet anotherexemplary embodiment, second conductive element 320 may be locatedadjacent to, and extend around, less than half of the surface edges offirst conductive element 310. Second conductive element 320 may also bearranged as a plurality of individual segments, instead of one unitarysegment as shown in FIG. 3. Moreover, second conductive element 320could be configured as a unitary segment and extend around a pluralityof different first conductive elements 310 (i.e., around a plurality ofdifferent buttons in a cluster, etc.) as, for example, a single commonguard ring. In such a configuration, each button (i.e., first conductiveelement 310) would have its measurement compared to the measurementassociated with the common guard ring (i.e., second conductive element320) to determine if a valid user input has occurred at that particularbutton.

First sensor 330 is coupled to first conductive element 310 and isoperative to measure a change in capacitance between first conductiveelement 310 and ground due to a change in the associated physicalenvironment. Second sensor 340 is coupled to second conductive element320 and is operative to measure a change in capacitance between secondconductive element 320 and ground due to the change in the associatedphysical environment. Although shown as separate elements in FIG. 3,first and second sensors 330 and 340 may also be embodied as a singlecombined sensor.

According to an exemplary embodiment, the change in the physicalenvironment associated with first and second conductive elements 310 and320 occurs in response to a user's tactile interaction with theapplicable apparatus, device and/or system. Such tactile interaction maybe intended by the user as a valid user input/button press (e.g., toactivate or de-activate the main power button, etc.), or may representan invalid user input/button press (e.g., stray touching of a buttonwhile moving device, etc.).

Controller 350 is coupled to first sensor 330 and second sensor 340, andis operative to determine a difference between the changes incapacitance measured by first sensor 330 and second sensor 340 as aresult of user input. According to exemplary embodiments, controller 350determines that a given change in the physical environment associatedwith first and second conductive elements 310 and 320 represents a validuser input to the applicable apparatus, device and/or system if thedetermined difference is equal to or exceeds a predefined threshold. Forexample, if a user presses directly in the center of the button (i.e.,the center of first conductive element 310), a relatively highcapacitance will be measured by first sensor 330 and a relatively lowcapacitance will be measured by second sensor 340.

Conversely, controller 350 determines that a given change in physicalenvironment associated with first and second conductive elements 310 and320 does not represent a valid user input to the applicable apparatus,device and/or system if the determined difference is less than thepredefined threshold. For example, the relative capacitance measured byfirst sensor 330 and second sensor 340 will be the same or similar if auser's palm or other body part is pressed up against first and secondconductive elements 310 and 320. The relative capacitance may also besimilar if someone presses their finger against both pads of first andsecond conductive elements 310 and 320.

Turning now to FIG. 4, an exemplary sensor circuit 400 according to anembodiment of the present disclosure is shown. Sensor circuit 400illustrates one of several possible circuits that may be used as part offirst sensor 330 and second sensor 340 (shown in FIG. 3) for sensing thechange in capacitance due to a user's tactile interaction with thebutton. Sensor 400 includes a programmable current source 410, arelaxation oscillator 420, precision analog comparator 430, a pulsewidth modulator 440, and a counter 450. The relaxation oscillator 420operates at a nominal frequency based on the property of the conductiveelement (e.g., conductive element 310 and conductive element 320)connected at the input and is further controlled by the current source410. The signal from the relaxation oscillator 420 is provided to theanalog comparator 430. The output of the comparator 430 is fed into theclock input of the pulse width modulator 440, which gates the counter450. Counter 450 also receives a clock input at a clock frequency usedin the device (e.g., receiving device 20 of FIG. 1 and/or receivingdevice 200 of FIG. 2).

In operation, an object, such as the user's finger, on the conductiveelement increases the capacitance which lowers the frequency of theoscillator 420. This lowered frequency effectively decreases the countmeasured in the pulse width modulator 440 and counter 450. Otherembodiments for capacitive sense circuits are possible and are wellknown to those skilled in the art. Further, portions of sensor circuit400 described in this embodiment may be shared between the operation ofmore than capacitive sensor device in order to reduce space, cost,and/or complexity.

As defined earlier, the present embodiments are intended to identifyfalse contact or button pushes by determining a difference between thechanges in capacitance occurring in a first sensor (e.g., sensor 330 inFIG. 3) and a second, or guard, sensor (e.g., sensor 340 in FIG. 3) as aresult of user input. Using the sensor circuit described in FIG. 4, thedifference between the changes in capacitance is determined by comparingthe counts measured for each of the sensor as a result of the change ofcapacitance. In one embodiment, a difference of 20 percent between thecount value for the first sensor and the count value for the secondsensor, with the first sensor value being lower, provides adetermination that a proper button contact has been made. As a result, acorresponding predefined threshold may be set at a value of 20 percentof the count value determined for the second or guard sensor (e.g.,sensor 340) when the first sensor count value is subtracted from thesecond sensor count value. It is important to note that in otherembodiments, a different percentage difference may be used. In stillother embodiments, using different sensor circuits, threshold valuesrelated to other determined parameters may be used.

Referring now to FIG. 5, an exemplary embodiment of a capacitive sensorelement arrangement 500 according to aspects of the present disclosureis shown. Arrangement 500 is similar in operation to elements 310, 315,and 320 shown in FIG. 3. However, arrangement 500 illustrates anon-uniform spacing 515 between element 510 and element 520, as wasdescribed earlier. Arrangement 500 may useful in environments thatrequire a variation in sensitivity to changes in capacitance between thesensor elements 510 and 520.

Referring now to FIG. 6, another exemplary embodiment of a capacitivesensor element arrangement 600 according to aspects of the presentdisclosure is shown. Arrangement 600 includes elements 610, 615, and620, which are similar in operation to elements 310, 315, and 320 shownin FIG. 3. However, arrangement 600 includes two main or first elements,element 610 and element 611, representing touch buttons for the user.Element 620 is located adjacent to, or otherwise surrounds both element610 and 611, providing a guard for both elements together, as wasdescribed earlier. Arrangement 600 may useful in environments thatrequire a touch guard for a set of two or more buttons withoutinfluencing contact between the buttons.

In a further perspective, FIG. 7A and FIG. 7B show a side view 700 of acapacitive touch button with guard with various user inputs according toan exemplary embodiment of the present disclosure. In particular, FIG.7A and FIG. 7B show a view of first and second conductive elements 710and 720. First and second conductive elements 710 and 720 may correspondto elements 310 and 320 shown in FIG. 3, or may correspond to theelements shown in FIG. 5 and/or FIG. 6. As indicated in FIG. 7A, a validuser input (i.e., button press) requires a user's finger 705 to pressthe center of first conductive element 710, resulting in an increase incapacitance on conductive element 710 without an increase in capacitanceon conductive element 720. Conversely, as shown in FIG. 7B, a user'spalm 706 or other type of accidental press by a user will cause agreater capacitance on both first and second conductive elements 710 and720 leading to the signal being rejected as an invalid user input. Inthis manner, the present embodiment allows, among other things, betteridentification of the accuracy of a user's finger press and a reductionin false triggering due to inadvertent contact with a touch pad orbutton.

Referring to FIG. 8, a flow diagram 800 according to an exemplaryembodiment of the present disclosure is shown. For purposes of exampleand clarity of description only, the steps of FIG. 8 are described belowwith specific reference to the exemplary embodiments of FIGS. 3 and 7described above. However, it should be intuitive to those skilled in theart that the inventive principles embodied in the flowchart of FIG. 8may also be applied to systems, apparatuses, devices and/orimplementations other than those specifically described herein.Accordingly, the steps of FIG. 8 are exemplary only, and are notintended to limit the applicability of the present disclosure in anymanner.

At step 810, a change in the physical environment related to first andsecond conductive elements 310 and 320 in configuration 300 occurs.According to an exemplary embodiment, the change in physical environmentoccurs at step 810 in response to a user's tactile interaction with theapplicable apparatus, device and/or system. Such tactile interaction maybe intended by the user as a valid button press (e.g., to activate orde-activate the main power button, etc.), or may represent an invalidbutton press (e.g., stray touching of a button while moving device,etc.).

At step 820, first sensor 330 detects and measures a change incapacitance between first conductive element 310 and ground due to thechange in physical environment that occurred at step 810.

At step 830, second sensor 340 detects and measures a change incapacitance between second conductive element 320 (i.e., the guardelement) and ground due to the change in physical environment thatoccurred at step 810.

At step 840, controller 350 determines a difference between the measuredchanges in capacitance of first sensor 330 and second sensor 340. Asindicated earlier herein, first and second sensors 330 and 340 may becombined as a single sensor.

At step 850, controller 350 determines if the difference determined atstep 840 is equal to or greater than a predefined threshold (e.g., avalue that is 20 percent of the value for second sensor 340). Suchthreshold may be initially set as a matter of design choice and/or beadjustable by a user of the applicable apparatus, device and/or system.According to exemplary embodiments, at step 850, controller 350determines that a valid user input to the applicable apparatus, deviceand/or system has occurred if the determined difference at step 840 isequal to or exceeds a predefined threshold. For example, if a userpresses directly in the center of the button (i.e., the center of firstconductive element 310), a relatively high capacitance will be measuredby first sensor 330 and a relatively low capacitance will be measured bysecond sensor 340

If the determination at step 850 is positive, process flow advances tostep 860 where controller 350 determines that a valid button press hasoccurred as a result of the change in physical environment at step 510.That is, if it is determined at step 850 that the difference determinedat step 840 equals or exceeds an established threshold, controller 350determines at step 860 that the change in physical environment thatoccurred at step 810 represents a valid user input to the applicableapparatus, device and/or system. As a result of this determination,controller 350 may output a control signal to enable or disable theperformance of a particular control function associated with theapplicable apparatus, device and/or system.

Alternatively, if the determination at step 850 is negative, processflow advances to step 870 where controller 350 determines that a validbutton press has not occurred as a result of the change in physicalenvironment at step 810. That is, if it is determined at step 850 thatthe difference determined at step 840 is less than the threshold,controller 350 determines at step 870 that the change in physicalenvironment that occurred at step 810 does not represent a valid userinput to the applicable apparatus, device and/or system. As a result ofthis determination, controller 350 may ignore the change in physicalenvironment that occurred at step 810.

The steps of FIG. 8 may also applied to arrangements, such as shown inFIG. 6, in which second conductive element 620 is configured as aunitary segment and extends around a plurality of different firstconductive elements 610 and 611 (i.e., around a plurality of differentbuttons in a cluster, etc.) as, for example, a single common guard ring.With such arrangements, each button (i.e., conductive element 610, 611)would have its respective measurement compared to the measurementassociated with the common guard ring (i.e., conductive element 620) todetermine if a valid user input has occurred at that particular button.Other types of modifications to the steps of FIG. 8 may also beimplemented according to principles of the present disclosure.

As described above, the present disclosure provides an improved designfor a capacitive touch button which includes a guard feature thatprovides, among other things, the ability to detect and reject falsetouches. Such an inventive capacitive touch button may be utilized withany type of device, apparatus and/or system that includes one or morecapacitive touch buttons.

While this disclosure has been described as having a preferred design,the present embodiments can be further modified within the scope of thisdisclosure. This application is therefore intended to cover anyvariations, uses, or adaptations of the embodiments using their generalprinciples. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains and which fallwithin the limits of the appended claims.

The invention claimed is:
 1. An apparatus, comprising: a firstconductive element, the first conductive element capacitively isolatedfrom ground; a second conductive element, the second conductive elementcapacitively isolated from ground and located adjacent to edges of thefirst conductive element; a first sensor coupled to the first conductiveelement, the first sensor measuring a change in capacitance between thefirst conductive element and ground due to a change in physicalenvironment; a second sensor coupled to the second conductive element,the second sensor measuring a change in capacitance between the secondconductive element and ground due to the change in physical environment;and a controller coupled to the first sensor and the second sensor, thecontroller determining a difference between the measured changes incapacitance of the first sensor and the second sensor, wherein if thedetermined difference is equal to or exceeds a threshold, the controllerdetermines that the change in physical environment represents a validuser input to the apparatus, and if the determined difference is lessthan the threshold, the controller determines that the change inphysical environment does not represent a valid user input to theapparatus.
 2. The apparatus of claim 1, wherein: the first conductiveelement represents a first portion of a capacitive touch button; and thesecond conductive element represents a second portion of the capacitivetouch button.
 3. The apparatus of claim 2, wherein the first portion ofthe capacitive touch button is a main portion of the capacitive touchbutton and the second portion of the capacitive touch button is a guardportion of the capacitive touch button.
 4. The apparatus of claim 2,wherein the capacitive touch button is a power button of the apparatus.5. The apparatus of claim 1, wherein: the first conductive element iscircular; and the second conductive element is concentric withsubstantially all of the first conductive element.
 6. The apparatus ofclaim 1, wherein the threshold is a value that is twenty percent of thevalue of the change in capacitance between the second conductive elementand ground.
 7. The apparatus of claim 1, wherein a gap between the firstand second conductive elements is uniform along their respective surfaceedges.
 8. The apparatus of claim 1, wherein a gap between the first andsecond conductive elements is not uniform along their respective surfaceedges.
 9. The apparatus of claim 1, comprising a plurality of the firstconductive elements, and wherein the second conductive element isconfigured as a unitary segment extending around the plurality of firstconductive elements.
 10. A method, comprising: measuring a change incapacitance between a first conductive and ground due to a change inphysical environment; measuring a change in capacitance between a secondconductive element and ground due to the change in physical environment,wherein the second conductive element is located adjacent to edges ofthe first conductive element; determining a difference between themeasured changes in capacitance; determining that the change in physicalenvironment represents a valid user input to an apparatus if thedetermined difference is equal to or exceeds a threshold; anddetermining that the change in physical environment does not represent avalid user input to the apparatus if the determined difference is lessthan the threshold.
 11. The method of claim 10, wherein: the firstconductive element represents a first portion of a capacitive touchbutton of an apparatus; and the second conductive element represents asecond portion of the capacitive touch button.
 12. The method of claim11, wherein the first portion of the capacitive touch button is a mainportion of the capacitive touch button and the second portion of thecapacitive touch button is a guard portion of the capacitive touchbutton.
 13. The method of claim 11, wherein the capacitive touch buttonis a power button of the apparatus.
 14. The method of claim 10, wherein:the first conductive element is circular; and the second conductivemeans is concentric with substantially all of the first conductivemeans.
 15. The method of claim 10, wherein: the first conductive elementcomprises a plurality of conductive elements; and the second conductiveelement is configured as a unitary segment extending around theplurality of conductive elements.
 16. The method of claim 10, whereinthe threshold is a value that is twenty percent of the value of thechange in capacitance between the second conductive element and ground.17. The method of claim 10, wherein a gap between the first and secondconductive elements is uniform along their respective surface edges. 18.The method of claim 10, wherein a gap between the first and secondconductive elements is not uniform along their respective surface edges.19. An apparatus, comprising: first conductive means capacitivelyisolated from ground; second conductive means capacitively isolated fromground and positioned adjacent to substantially all surface edges of thefirst conductive means; means for measuring a change in capacitancebetween the first conductive means and ground due to a change inphysical environment, and for measuring a change in capacitance betweenthe second conductive means and ground due to the change in physicalenvironment; and means for determining a difference between the measuredchanges in capacitance, wherein if the determined difference is equal toor exceeds a threshold, the determining means determines that the changein physical environment represents a valid user input to the apparatus,and wherein if the determined difference is less than a threshold, thedetermining means determines that the change in physical environmentdoes not represent a valid user input to the apparatus.
 20. Theapparatus of claim 19, wherein: the first conductive means represents afirst portion of a capacitive touch button; and the second conductivemeans represents a second portion of the capacitive touch button. 21.The apparatus of claim 20, wherein the first portion of the capacitivetouch button is a main portion of the capacitive touch button and thesecond portion of the capacitive touch button is a guard portion of thecapacitive touch button.
 22. The apparatus of claim 20, wherein thecapacitive touch button is a power button of the apparatus.
 23. Theapparatus of claim 19, wherein: the first conductive means is circular;and the second conductive means is concentric with substantially all ofthe first conductive element.
 24. The apparatus of claim 19, wherein thethreshold is a value that is twenty percent of the value of the changein capacitance between the second conductive element and ground.
 25. Theapparatus of claim 19, wherein a gap between the first conductive meansand second conductive means is uniform along their respective surfaceedges.
 26. The apparatus of claim 19, wherein a gap between the firstconductive means and second conductive means is not uniform along theirrespective surface edges.
 27. The apparatus of claim 19, wherein thefirst conductive means comprises a plurality of the first conductiveelements, and wherein the second conductive means is configured as aunitary segment extending around the plurality of first conductiveelements.